One of the features that network geeks are looking for, is a graphical way to build network topologies with VirtualBox.I decided to provide such a way, and patched the community's GNS3 Graphical Network Simulator for VirtualBox support.

GNS3 feels very much as an extension of VirtualBox, providing more network capabilities and configuring VirtualBox VM's networks automatically, yet it is not intrusive, and allows you to use every single feature of the standard VirtualBox.

GNS3 has several killer features:

1. Cross-platform -- GNS3 runs on all platforms, that are supported by VirtualBox. Namely: Windows, Linux, Mac OS X, Solaris, FreeBSD. 2. uses Qt4 GUI library (same as VirtualBox) -- very intuitive and user-friendly. 3. Dynamic Topology layer -- items (VMs/Routers/Switches/Cables) can be added or removed at run-time, without shutting down devices or topology. (provided by 'Dynagen' component) 3.a. Topology can be connected to Real physical networks by means of "Cloud". 4. Live Traffic Capture -- full integration with Wireshark.5. Very easy and readable text format (for saving topology) 6. Three underlying engines: Dynamips (Routers+Switches), Qemu and VirtualBox (for VMs). 6.a. It is recommended to install all 3 engines to enjoy full power of GNS3, but installing only VirtualBox and skipping 2 others is possible. 7. Multi-host -- distributed architecture. (although most of our users run everything on 'localhost') 8. GNS3 is intended as education tool. 9. Tight integration with VirtualBox 10. Open-Source -- GNS3 is GPLed (written in python)